Grinding apparatus



June 16, 1964 K. ZWlCK 3,137,108

GRINDING APPARATUS Filed April 10, 1963 United States Patent I 3,137,108GRINDING APPARATUS Kurt Zwick, Munich, Germany, assignor toFeinmechaniir G.m.b.H., Weilheirn, Germany, a company of Germany FiledApr. 10, 1%3, Ser. No. 272,065 Claims priority, application Germany Apr.25, 1962 i 7 Claims. (Cl. 51-273) This invention relates to grindingapparatus, and more particularly to the type of grinding apparatus. inwhich a grinding wheel or like movable member of abrasive material isenclosed in the cavity of a casing connected to dust collectingequipment and provided with a minimum number of apertures for access ofthe work piece to be 'groundand of a grinding wheel dressing tool.

As is well known, abrasive working of a workpiece creates dust, and evenmore dust is usually formed when the grinding wheel is dressed. Toprotect workers from the dust, it is conventional to enclose grindingwheels in a casing as far as is consistent with proper operis free toescape through the opening intended for the dressing tool duringgrinding while the other opening is at least partly obstructed by thework piece and the hand holding the work piece. Conversely, dust escapesduring wheel dressing through the opening intended for the work piece.If the suction of the exhaust equipment is sufliciently increased tominimize dust escape through the unused opening, much air is drawn intothe casing.

through the unobstructed opening, and the exhaust equipment is operatedat very low efficiency. 7

It is the object of the invention to provide a grinding apparatus of thetype described in which the exhaust system may be operated efficientlyand economically without permitting the escape of dust from the'twospaced apertures available in the casing for insertion of a workpiece and of a dressing tool respectively. 1

Other objects and features of the invention will become apparent tothose skilled in the art as the disclosure is made in the followingdetailed description of a preferred embodiment of the invention asillustrated in the accompanying sheet of drawing in which:

FIG. 1 is a fragmentary front-elevational view of a grinding apparatusof the invention;

FIG. 2 shows the apparatus of FIG. .1 in fragmentary side elevation;

FIG. 3 illustrates the apparatus of FIG. 1 in sideelevational section onthe line III-Ill;

FIG. 4 shows the apparatus of FIG. 1 in a differentoperational position;and

FIG. 5 shows the apparatus of FIG. 4 in a view corresponding to FIG. 3.

Referring now to the drawing in detail, and initially to FIGS. 1 to 3,there is shown a casing 12 in which a cup shaped grinding wheel isrotatably mounted on a drive shaft 11. The cavity of the casin'g'12 inwhich the wheel FIGS. 1 and 2, a portion of the grinding wheel It) isexposed to the atmosphere and accessible to a tool bit 22 for grindingof the latter on a radial face of the Wheel 10. To permit entry of thetool bit 22 into the casing cavity, the circumferential cylindrical wallof the casing 12 has an aperture 16 extendingcircumferentially over anarc of about 130, and the cover 14 has a peripheral cutout 18 adjacentthe aperture 16 and of similar'cir'cumferential length. A guide member1'7 on the casing 12 guides the tool bit toward the wheel 10. The cover14 further has an elongated slot 20 which is arcuate about the axis of apivot pin 21'which is rotatable and axial slidable in the casing 12. Theaxis of rotation of the pin 21 is parallel to that of the drive shaft.11.

The pin 21 is integral with a radial arm 24 which constitutes a dressingtool carrier. The dressing tool is not shown in the drawing. It may beof the type disclosed in my copending, simultaneously filed applicationSerial No. 272,064, and consists of an elongated rod from which adiamond projects in a longitudinal direction. The rod may be inserted inthe bore 23 of the arm 24, and secured therein by means of a set screw25. I

A cup shaped closure member 26 is rotatably mounted on the cover 14coaxially with the grinding wheel 10. The closure member consists of abottom portion 28 extending in a radial plane, and of a substantiallycylindrical wall portion 30. The open side of the closure member facesinward of the cavity in the casing 12.

The bottom portion 28 is formed with a passage 32 having the approximateshape of a sector of a circle. It extends over an arc of about 60 at therim of the bottom portion 28, and tapers in a radially inward direction.An axial slot 34 in the wall portion 30 communicates with the passage32. A knob 36 rotatably secures-the closure member 26 on the cover 14,and permits the closure member to be turned by hand.

In the position illustrated in FIGS. 1 and 2, the closure member ispositioned in such a manner that the passage 32 registers with theexternal orifice of the cut-out 18, and the slot 34 registers with thecorresponding orifice of the apertures 16, thus connecting the casingcavity to the ambient atmosphere, and opening a path for the entry ofthe tool bit 22 into the cavity of the casing 12 for grinding on aradial face of the wheel 10. The arcuate slot '20 is blocked by animperforate part of the bottom 7 portion 28.

' When it is desired to dress the grinding wheel 10, the knob 36 isturned until the imperforate part of the cylindrical wall portion 30blocks the aperture 16, and a corresponding part of the bottom portionblocks the cutout 18, while the passage 32 is aligned with the arcuatelyelongated slot 20 for axial entry of a dressing tool. The dressing toolis mounted on the arm 24, and introduced through the slot 20 by axialand pivoting movement of the pin 21. It is then pivoted hack and forthabout the axis'of the pin 21 to dress the radial face of the wheel 10.

A change from the position of the grinding apparatus illustrated inFIGS. 1' and 2 to that shown in FIGS. 4 and 5 requires rotation of theknob 36 through an angle of approximately and cooperating abutment meansmay be provided on the knob and on the cover 14 to limit movement of theclosure member accordingly.

While the grinding apparatus of the invention provides different andcircumferentially spaced apertures for insertion of a Work piece to beground and of a dressing tool, dust cannot escape and air cannot bedrawn into the casing in significant amounts through one aperture whilethe other one is being used.

Various modifications are contemplated and may obviously be resorted toby those skilled in the art without departing from the spirit and scopeof the invention as hereinafter defined by the appended claims,.as onlya preferred embodiment thereof has been disclosed.

. What isclaimcd is:

1. In a grinding apparatus, in combination:

(a) a casing having an axis and defining a substantially closed cavityabout said axis, said casing being formed with two spaced passagesconnecting said cavity with the ambient atmosphere;

(b) an abrasive grinding member rotatable about said axis in saidcavity;

(c) closure means mounted on said casing and movable between a firstoperative position in which one of said passages is blocked by saidclosure means while the other passage communicates with the atmosphere,and a second operative position in which said other passage is blockedby said closure means and said one passage communicates with theatmosphere; and V (d) exhaust means communicating with said cavity forwithdrawing air and dust therefrom.

2. In an apparatus as set forth in claim 1, said closure means includinga closure member rotatable about said axis between said operativepositions, said closure mem ber being formed with an aperture thereinpositioned for registering alignment with a respective passage ineach ofsaid positions.

3. In an apparatus as set forth in claim 2, manually operable means forrotating said closure member about said axis. v

4. In a grinding wheel, in combination:

(a) a casing having an axisand defining a substantially closed cavityabout said axis,

(1) said casing being formed with two passages connecting said cavitywith the ambient atmosphere,

(2) said passages having respective external orifices facing axially andradially relative to said axis; a

(b) an abrasive grinding member rotatable about said axis in saidcavity; and

(c) a cup-shaped closure member mounted on said casing for rotationabout said axis between a first operative position in which one of saidpassages is blocked by said closure member while the other passagecommunicates with said atmosphere, and a second operative position inwhich said other passage is blocked by said closure means and said onepassage communicates with the atmosphere,

(1) said closure member having respective wall portions extending in' aradial plane relative to said' axis in a cylindrical surface about saidaxis,

(2) said wall portions being formed with contiguous respective aperturesjointly alignable with a respective orifice in each of said operativepositions.

5. In an apparatus as set forth in claim 4, exhaust means communicatingwith said cavity for withdrawing air and dust therefrom.

6. In an apparatus as set forth in claim 5, one of said orifices andsaid contiguously communicating apertures jointly defining an elongatedopening when in alignment,

a dressing tool carrier mounted on said casing for pivotal movement, andfastening means on said carrier for fastening a grinding wheel dressingtool to said carrier in dressing engagement with said grinding memberthrough said l elongated opening, and for movement of said toollongitudinally of said elongated opening and radially with respect tosaid axes during said pivotal movement of said carrier member.

' 7. In an apparatus as set forth in claim 6, the other 4 one of saidorifices and said contiguously communicating apertures jointly defininganother opening when in alignment, and guide means on said casing forguiding a work piece to be ground on said abrasive member inward of saidcavity through said other opening.

References Cited in the file of this patent UNITED STATES PATENTS967,729 Charpentier Aug. 16, 1910 1,797,293 Mcllvane Mar. 24, 19312,064,871 Angradi Dec. 22, 1936 2,414,797 Brown Jan. 28, 1947 2,426,478Whipple Aug. 26, 1947 FOREIGN PATENTS 634,651 Germany Sept. 1, 1936

1. IN A GRINDING APPARATUS, IN COMBINATION; (A) A CASING HAVING AN AXISAND DEFINING A SUBSTANTIALLY CLOSED CAVITY ABOUT SAID AXIS, SAID CASINGBEING FORMED WITH TWO SPACED PASSAGES CONNECTING SAID CAVITY WITH THEAMBIENT ATMOSPHERE; (B) AN ABRASIVE GRINDING MEMBER ROTATABLE ABOUT SAIDAXIS IN SAID CAVITY; (C) CLOSURE MEANS MOUNTED ON SAID CASING ANDMOVABLE BETWEEN A FIRST OPERATIVE POSITION IN WHICH ONE OF SAID PASSAGESIS BLOCKED BY SAID CLOSURE MEANS WHILE THE OTHER PASSAGE COMMUNICATESWITH THE ATMOSPHERE, AND A SECOND OPERATIVE POSITION IN WHICH SAID OTHERPASSAGE IS BLOCKED BY SAID CLOSURE MEANS AND SAID ONE PASSAGECOMMUNICATES WITH THE ATMOSPHERE; AND (D) EXHAUST MEANS COMMUNICATINGWITH SAID CAVITY FOR WITHDRAWING AIR AND DUST THEREFROM.